Abstract
A study was carried out in rats (prepared for chronic sleep recording) of the effects of pretreatment with neuroleptics differing in their relative antinoradrenaline and antidopamine receptor potencies, on the l‐DOPA and (+)‐amphetamine‐induced increase in waking EEG.
Haloperidol (0.6 mg/kg), which blocks central dopamine and noradrenaline (NA) receptors, reversed the EEG desynchronizing actions of l‐DOPA and (+)‐amphetamine.
Low doses of pimozide (0.4 to 0.8 mg/kg) which block dopamine receptors exclusively, were not able to modify the pharmacologically induced disruption of the sleep‐awake cycle. However, at 1 mg/kg, a dose which also produces blockade of NA receptors, pimozide counteracted the increase in waking elicited by (+)‐amphetamine.
Spiroperidol (1 to 4 mg/kg) which is devoided of NA receptor blocking properties, failed to reverse the l‐DOPA or (+)‐amphetamine‐induced arousal.
Our results suggest that the increased waking time observed after the catecholamine agonists is related to an increased availability of NA rather than dopamine.